The cells of the granulated convoluted ducts in mouse submandibular gland synthesize, store and secrete several biologically important polypeptides. These include the nerve growth factor (NGF), the epidermal growth factor (EGF), peptide hydrolases and renin. The objectives of the proposed study are: 1. to establish the exact cellular and subcellular localization of NGF, EGF, renin and some of the peptide hydrolases; 2. to analyze the secretory mechanism involved in the transport, storage and discharge of these polypeptides; and 3. to investigate the secretory control mechanisms, which regulate the discharge of these substances and 4. the rate of synthesis at different phases of the secretory cycle. The data will provide information on the physiologic roles of the submandibular gland polypeptides of potentially great importance.